Shoulder bag strap



FIG. 1 is a left side elevational view of a shoulder bag strap showing my design;

FIG. 2 is a right side elevational view thereof;

FIG. 3 is a front elevational view thereof, the broken line showing of a person with bag is environmental only and form no part of the claimed design. 

The ornamental design for a shoulder bag strap, as shown and described. 